Study type: Epidemiological study (observational study)

Mental health status of employees in substations of electromagnetic fields at extremely low frequency in Tehran epidem.

Published in: Iranian J Environ Health Sci Eng 2006; 3 (3): 217-221

Aim of study (acc. to author)

A study was conducted in Iran to investigate the association between occupational exposure to extremely low frequency magnetic fields in substations and mental health status.

Further details

The participants were asked to fill in a questionnaire (Symptom Check-List-90-Revised) to assess the mental health status. The questionnaire consists of 90-item questions including somatization, obsession and compulsion, interpersonal sensitivity, depression, anxiety, hostility, phobic anxiety, paranoid ideation, and psychoticism. Score rating based on a 5-point scale evaluates the individual mental status during the last week. Scoring and interpretation of results are achieved according to three indices: Global Severity Index (GSI), Positive Symptom Distress Index (PSDI), and Positive Symptom Total (PST). GSI shows the level or severity of disorder and gives information about the number of symptoms and severity of distress. PSD simply measures the number of symptoms that are reported positive by the examinee. PSDI is pure measurement of distress severity.

Endpoint/type of risk estimation


Exposure groups

Group Description
Reference group 1 employees of power stations working in the administration without exposure to electromagnetic fields
Group 2 employees of power stations exposed to electromagnetic fields


Case group

Control group

Study size

Cases Controls
Participants 101 101
Evaluable 99 98

Results (acc. to author)

There are statistically significant differences in Global Severity Index (GSI) and Positive Symptom Total (PST) between the case group and the control group. Positive Symptom Distress Index (PSDI) showed no significant difference between the two groups. Cases had also higher scores in all subscales in comparison with the control group. It was statistically significant for subscales of somatization, depression, anxiety, hostility and phobia. No correlation was found between age, marital status and split-shift working with GSI scores.
The authors concluded that occupational exposure to extremely low frequency magnetic fields in substations can lead to the development of mental disorders. However, the results need confirmation by other controlled trials.

Related articles